Impact of pressure in static and dynamic pressing of zirconia ultradisperse powders on compact density and compaction efficiency during sintering

Porous Al2O3/Al catalyst supports were fabricated using a mixture of Al(OH)3 and Al powders, followed by pressureless sintering at a temperature of 600 °C in vacuum. Different pressures were used to prepare green compacts. High compaction pressure led to a high surface area and good mechanical and electrical properties for the sintered specimens. However, when the Al content in the sintered specimen exceeded a definite value, high compaction pressure decreased the surface area abruptly. Scanning electron microscopy observations revealed that agglomeration in the starting mixture has a significant effect on the microstructure of the sintered specimens. High compaction pressure greatly eliminated the agglomerates and led to a uniform microstructure for the sintered specimens. However, when the Al content in the starting mixture was too high, Al particles in the compacts prepared by the high pressure were largely sintered due to the high compact density so that most of the pores were closed. The present study indicates that a suitable compaction pressure is critical to obtaining superior Al2O3/Al supports.

Download Full-text

Third-Harmonic Generation in Special Parabolic Quantum Wells

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.760-762.392 ◽

2013 ◽

Vol 760-762 ◽

pp. 392-396

Author(s):

You Bin Yu

Keyword(s):

Quantum Well ◽

Density Matrix ◽

Quantum Wells ◽

Harmonic Generation ◽

Third Harmonic Generation ◽

Third Harmonic ◽

The Third ◽

Compact Density ◽

Asymmetric Quantum ◽

Parabolic Quantum Wells

Third-harmonic generation in a special asymmetric quantum well is investigated. The third-harmonic generation coefficient is carried out by applying compact-density-matrix method. The numerical results are presented for a GaAs/AlGaAs asymmetric quantum well. The very large third-harmonic generation coefficient is obtained in this quantum well. Moreover, the third-harmonic generation coefficient dependents on the quantum well parameters are investigated, respectively.

Download Full-text

Densification of a viscous porous solid during dynamic pressing

Soviet Powder Metallurgy and Metal Ceramics ◽

10.1007/bf00796453 ◽

1973 ◽

Vol 12 (10) ◽

pp. 790-796

Author(s):

M. S. Koval'chenko

Keyword(s):

Porous Solid ◽

Dynamic Pressing

Download Full-text

Effects of chemistry and compact density on decomposition of PM lubricants

Metal Powder Report ◽

10.1016/0026-0657(94)90757-9 ◽

1994 ◽

Vol 49 (11) ◽

pp. 40

Keyword(s):

Compact Density

Download Full-text

ELECTRO-OPTIC EFFECT IN A SEMI-PARABOLIC QUANTUM WELL WITH AN APPLIED ELECTRIC FIELD

Modern Physics Letters B ◽

10.1142/s0217984903005366 ◽

2003 ◽

Vol 17 (09) ◽

pp. 347-354 ◽

Cited By ~ 28

Author(s):

LI ZHANG ◽

HONG-JING XIE

Keyword(s):

Electric Field ◽

Quantum Well ◽

Applied Electric Field ◽

Field Effect ◽

Harmonic Oscillation ◽

Electric Field Effect ◽

Confining Potential ◽

Compact Density ◽

Electro Optic ◽

Potential Frequency

By using the compact density matrix approach, the electro-optic effect (EOE) in a semi-parabolic quantum well (QW) with an applied electric field has been theoretically investigated. Via a variant of displacement harmonic oscillation, the exact electronic states in the semi-parabolic QW with an applied electric field are obtained. Numerical results on typical GaAs material reveal that the electro-optic effect nearly linearly increases with the increasing of magnitude of the electric field, but it monotonously decreases with the increasing of confining potential frequency of the semi-parabolic QW. The EOE in the model investigated is 102 times larger than that in the symmetric parabolic QW under the same electric field and the same frequency of parabolic confining potential, which is due to the self-asymmetry of the system and the electric field effect.

Download Full-text